The present invention relates to trailer-type vehicles for lifting, transporting, and depositing loads.
In particular, the invention relates to a vehicle of the above type which has a lower substantially U-shaped frame, which is open at its rear, and a similar upper U-shpaed frame connected to the lower frame in such a way that the upper frame can be moved downwardly with respect to the lower frame to a load-receiving position and upwardly with respect to the lower frame to a load-transporting position, while a load can also be deposited when the upper frame is in its lower position. This upper frame is also turnable about a transverse pivot axis for depositing a load. Suitable power means, such as hydraulic piston-and-cylinder assemblies, which preferably are double-acting, may be situated on opposite sides of the space for accommodating a load and connected with the frames for displacing the upper frame with respect to the lower frame between the above positions as well as for turning the upper frame about the above pivot axis when depositing a load.
Loading and dumping mechanisms of the above general type are known in connection with transporting vehicles. In the known mechanisms double-acting hydraulic systems have been utilized, for example, in such a way that relatively long hydraulic cylinders are disposed on both sides of the load-receiving space, these cylinders of course accommodating pistons which have piston rods extending from the cylinders, and the opposed ends of such systems are respectively connected with the upper and lower frames in such a way that the lower end of each hydraulic system is situated near the rear of the lower frame and the upper end of each hydraulic system is situated near the front part of the upper frame. In order to lower the upper frame from its transporting position to its load-receiving position, the hydraulic systems of the above type are contracted while the depositing or dumping of a load is achieved by expanding these hydraulic systems. However, these known constructions have certain disadvantages. One of these disadvantages resides in the fact that the piston rods of the hydraulic systems are unprotected and exposed to damage particularly in the transporting position of the upper frame. In addition, the length of these hydraulic systems and that of the hydraulic tubing associated therewith becomes unfavorably great. Also, a drawback of the conventional constructions resides in the fact that the frames have a certain ineffective length resulting from the fact that the pivot axis for the load-depositing structure is situated unfavorably at a location much too near to the front of the vehicle, so that the load which is deposited also is deposited too near to the front of the vehicle.
A still further drawback of the conventional constructions resides in the fact that when a load is initially raised there is at the same time an undesirably large forward component of movement in a horizontal direction, with the result that the load is unavoidably dragged along the ground before it is lifted clear of the ground. Also, drawbacks reside in a manner in which locking arrangements are provided for securing the load and the frame to each other.
A further serious drawback encountered with known devices of the prior art resides in the fact that such devices are designed only for a given size and type of load. Thus, for different types and sizes of loads it is necessary at the present time to utilize different vehicles.